1. Field of Invention
The present invention relates to a KVM switch. More particularly, the present invention relates to a KVM switch operated as a terminal system.
2. Description of Related Art
With the rapid development in information technology, computers and their peripherals have become very popular. Typically, each computer is equipped with one set of user interface devices, and may including a keyboard, a mouse and a monitor. However, this equipment wastes money and occupies too much space if one has several computers. Therefore, a keyboard-video-mouse (KVM) switch is proposed to use at least one set of user interface devices to manage several computers and their peripherals. Using the KVM switch reduces hardware costs and decreases waste of space while simultaneously conquering the problem of compatibility between different interfaces.
FIG. 1 is a schematic view depicting a traditional KVM switch. Each of computers 114 is connected to a switching device 102 through its respective I/O module 104, and each of sets of user interface devices 116 is connected to the switching device 102 through its respective console module 106. The switching device 102 routes paths between the computers 114 and the sets of user interface devices 116. In some practical applications, the switching device 102, the I/O modules 104 and the computers 114 are located in a data center (dash region), which may be far from the console modules 106 and the sets of user interface devices 116 located in other rooms.
The examples of the switching device 102 include KM0432 manufactured by ATEN International Co., LTD.; the examples of the console module 106 include ATEN KA 9270 and KA 9220; and the examples of the I/O module 104 include ATEN KA 9120, KA 9130, KA 9131 and KA 9170.
In the traditional configuration, when one console module 106 receives an OSD (On Screen Display) instruction input from a keyboard or a mouse of its respective set of user interface devices 116, such as a keyboard signal or a mouse signal, the console module 106 typically processes the OSD instruction to generate an OSD image on its own. More particularly, the OSD image is generated based on a new display content update by a console processor of the console module 106 itself, without processing from either the switching device 102 or the I/O modules 104. The console module 106 captures the OSD instruction, decides what should be displayed, and then overlaps the OSD image on the original video signal.
However, the traditional configuration of the KVM switch seems to give a limited system, in which all necessary information possibly used in the OSD image must have been saved before deciding what is to be displayed, and thus the traditional configuration limits the functions and reduces the compatibility of the console module 106. Moreover, if the necessary information is too large to be saved in one console module 106, some memory management techniques may be applied or expensive memories may be added, incurring added costs and design difficulty. In addition, if the firmware needs to be upgraded, every console module 106 has to be individually upgraded because each responds only to its own OSD, and the upgrade procedure certainly takes time and waste effort.